Furnace



Feb. 19, 1929. 1,702,597

1. w. FoL'lrz FURNAGEv I Filed Oct. 16. 1920 Patented eb. 19, 1929.

UNITED l STATES ma w. romz,v or cincaoo, ILLINoIs.

IUBNAGE.

Application mea october 1e,B 1920. serialv No. 417,443.

This invention relates to a furnace'of that general class where at least a part of the air supplied to the fuel is preheated. The purposes of the invention are to provide a practical design for use in connection with steam boilers and for rendering a furnace more eiicient for heating the boiler, and incidentally preventing loss of fuel in the products of combustion.

These objects are accomplished by the use of certain air conduitsin conjunction wit reflecting pier formations, all of which are constructed within the brick setting surrounding the boiler.

By means of the air conduits the proper quantity of preheated air is suppliedto the furnace over order to maintain all the combustible gas at the ignition temperature, and thereby render it less possible for any portion of the gases that are expelled from the coal to remain below the kindling point in temperature and pass away unconsumed.

By means of the piers the current of hot air and gas in the furnace is broken up by its direct impact upon the piers, and thereby an extensive admixture of the air and gases is attained in the early stages of combustion.

The burning of bituminous coal with maximum economy can not be attained in any of the furnaces now in common use.

This furnace is especially designed to burn with high efficiency and without smoke, coal that contains large quantities of volatile matter, and is the result of many years of experiment-ing in actual 'furnace practice in connection with steam boilers, with mechanical stokers as well as with hand-fired equipment. In constructing lthis furnace the following elements were carefully considered: (1) the kindling temperature of the gases of the coal; (2) the quantity of air required under average conditions; (3) the time necessary to complete combustion; (4) the dimensions o the irebox, combustion chamber, breaching and stack; (5) the movement of the current of hot air and gas necessary to cause the gas to properly combine with the oxygen of the air. By means of this furnace the gases produced from the burning coal are ignited near the point of their liberation, excess air can be eliminated by proper control of the ashpit doors or of the stack damper, and a fairly uniform temperature can be maintained throughout the furnace, and thereby all the combustible elements of the coal are conthe top of the burning fuel in sumed, the quantity of ash and clinkers reduced to a minimum, the heating surface of the boiler kept clean, and the capacity and efficiency of the boiler increased.

These objects are accomplished by the device shown in the accompanying drawings, in which Figure 1 is a longitudinal sectional view of the wall structure of a furnace constructed a`cording to this invention and shows the h boiler in side elevation. The view is taken on the line 1-1 of Fig. 2. j

Figure 2 is a sectional plan view taken on the line 2-2 of Figure 1', but with the grate omitted.

The design shown in the drawings comprises a boiler.1 surrounded by the usual wall structure 2 but containing the piers 3 and 4 and the wings 5. The pier 3 is centrally located on the bridge 4, thus providing the two throats 6 and 7 opposite the wings 5. These wings therefore provide reflecting surfaces at right angles to the currents passing through throats 6 and 7. Further the throat 8 between the wings 5 directs the 'currents against the face of pier 4 causing a second reflection and eddying of the gas and air mixture.

Air is supplied to the furnace as usual through the ash-pit door 9, but a portion of the air entering the ash-pit and depending upon the condition ofthe fuel bed on the grate 10 is caused to enter the inlets 11 of a pair of conduits 12. These inlets are located well above the floor ofthe ash-pit so that the air passage will not be interfered with by ashes in the pit. The inlet 11 of the conduits communicates with longitudinal portions 13 thereof in the side walls of the furnace. The portions 13 of the conduits by branches 14 in the bridge wall communicate with the legs of U-shaped parts 16 of the conduits 12. The U-shaped parts of the conduits are located in f the iioor of the combustion chamber which is a tile and cement structure. The legs'l? of the U-sha ed parts of the conduits communicate wi return parts 18 located in the bridge wall and for conducting the heated air into longitudinal channels 19 in the side walls adjacent the fire-box and above the location of the. grate. The portions 19 of the conduits have outlets 20 above the normal level of the fuel on the grate. The parts 15 and 17 of the conduits which extend longitudinally along the floor of the combustion chamber pass through the bridge wall in order to provide clean-out doors 21, access to which may be had through the ash-pit.

Steam under a few pounds pressure is found sufficient for the purpose of cleaning out the air conduits. The specific arrangement of these conduits as above described is found in practice to provide for the desired yfuel bed is maintained on the grate. The air entering the ashpit door has a free passage through the conduits 12 while a limited quantity of the air works its way slowly through the fuel bed. The air passing through the conduits becomes heated at the bridge wall and while passing through the floor of the combustion chamber and in the wall around the grate before being delivered to the rebox through the outlets 20. The temperature of this air under normal working conditions is substantially correct in proportion to the rate of flow of the products of combustion through the furnace to insure prompt ignition of the gases arising from the fuel bed. In furnaces having no means for directing a secondary supply of air to the fire-box, there is usually a leakage of air through the lire-door which is produced by the suction of the draft when the fuel on the grate becomes so packed as to prevent the free'passage of air from the ashpit upwardly through the grate. y,The provision of free passages for air leading from the ashpit to the fire-box, reduces the amount of leakage through the fire-door. Such leakage chills the gases so that a portion thereof may never reach the ignition point, but pass through the furnace unconsumed. The heated air and gas mixture in passing through the throats 6 and 7 is directed against the wings 5 andthen by passing through the throat 8 is directed against the pier 4, with the result that the current formation is thoroughly broken. These wings and the pier serve to reflect the heat and to tend to throw back the currents of burning gases, maintaining thesame in the incandescent stage a sufficient length of time to insure efficient combustion.

The air conduits are so constructed that the quantity of air passing through them and the temperature thereof are commensurate with the normal rate of combustion and the general temperature of the furnace, and thereby prompt ignition of the gases arising from the fuel bed is insured, and whereby the introduction of cold air into hand-fired furnaces may be lessened owing to the fact that the firing doors, without causing objectionable smoke, may be kept constantly v fired furnaces as well as to those that are hand fired. It is equally adaptable to forced draft, induced draft and natural draft. It may be successfully applied to old furnaces that havebeen long in use as well as in new furnace settings. In other words, it can be universally applied, including an effective .application of the same to all kinds of furnaces in which gas, oil or pulverized coal is used for fuel. The entire air supply is usually in the ashpit. When natural or induced draft is employed the entire air supply of the furnace is usually introduced through the ashpit door into the ashpit from whence it is distributed through the furnace in proper proportion. When forced draft is employed the ashpit is usually sealed except at the grate, and the entire air supply is then forced into the ashpit (or air compartment) below the grate through an air pipe or wind box, by means of ablower, and in this case, su'ch air pipe or wind box is tapped to supply suiicient air for said air conduits. In all cases a large portion of the air passes up through the grate and fuel thereon while an other portion of the air is caused to by-pass through the air conduits to the fire-box over the top of the fire therein. At all times in all cases the quantity of air passing through the air conduits is commensurate with the quantity of fuel distributed over the grate, together with the rate of combustion' of the fuel and the temperature of the furnace. In the application of this invention to the numerous designs of furnaces in common use,

no change is required in the regular and usual method of their operation. The invention balances and synchronizes with other furnace equipments to which it may be atl vcomplet-ely oxidized; that the res will be hotter; that he can get a greater capacity from the boiler with less fuel than he had been accustomed to burn; that theheating surfaces of the boiler will be more free from `carbon and soot deposits than formerly; that the quantity of ash and clinkers will be about one-half the amount usually produced, and that by reason of the cleaner combustion of the fuel and less reducing atmosphere in the furnace, the walls of the furnace will require much less repairs than usuali Supreme efficiency can be attained by the use of this invention when the furnace is operated at eX- treme capacity.

I claim:

1. A furnace comprising surrounding walls forming fire-box, ashpit and combustion chamber, and an unbroken continuous air conduit incased in one of the walls of said combustion chamber, said air conduit horizontally disposed and having an inlet located below the grate toward the front thereof and having an outlet located above the grate toward the front of the lire-box.

f branches passing through the bridge Wall and lof said combustion chamber,

2. A furnace comprising surrounding walls forming a tire-box, \ashpit and combustion chamber, and an unbroken continuous air conduit ineased in one ofthe walls of said combustion chamber, said air conduit horizontally disposed and extending in and along the side Walls of the furnace adjacent the fireboX and having an inlet located below the grate toward the front thereof and having an outlet located above the grate toward the front of the fire-box. j

3. A furnace comprising surrounding walls forming a fire-box'fashpit and combustion chamber, and unbroken continuous U-shape'd air conduits in the lateral sides of the floor of said combustion chamber, and having lateral in and along the side walls of the furnace adjacent the fire-box, these branches having inlets locatedin the ashpit towards the front thereof and outlets located in the tire-box towards the front thereof.

4. A furnace comprising surrounding walls forming fire-box, ashpit and combustion chamber, and unbroken continuous U-shaped air conduits in one ofthe Walls of said combustion chamber, and having lateral branches extending in and alongthe side walls of the furnace adjacent to the fire-box, these branches being horizontally disposed and having inlets located in the ashpit toward the v front thereof and outlets located in the lirebox toward the front thereof.

5. A furnace comprising surrounding Walls forming fire-box, ashpit and combustion chamber, and unbroken continuous U-shaped air conduits Yin one of the walls of said combustion chamber, and having lateral branches extending in and along the side walls of the furnace adjacent to the fire-box, these branches being horizontally disposed and having inlets located below the grate toward the front thereof and having outlets located zbove the grate toward the front of the fire- 6. A furnace comprising surrounding walls forming ashpit, fire-box and combustion chamber, and an unbroken continuous U- shaped air conduit incased in one of the walls said air conduit being horizontally disposed and having an inlet located .below the grate toward the front system of draft by delivering over the top of the fire therein a quantity of highly preheated air commensurate with the quantity of fuel distributed over the grate therein, together with the rate of the combustion of said fuel and the temperature of said furnace.

7 A furnace comprising surrounding walls forming ashpit, {ire-bor. and combustion chamber, and unbroken air conduits in the lateral sides of the floor of said combustion chamber, and having lateral branches passing through the bridge wall and in and along the side walls of the furnace adjacent to the fire-box, these branches beinef horizontally disposed and having inlets and outlets respectively located below and above the grate, to accommodate said furnace automatically Wit-h any system of draft by delivering over the top of the fire therein a quantity of highly pre-heated air commensurate with the quantity of fuel distributed over the grate therein, together with the rate of the combustion of said fuel and the temperature in said furnace.

8. A furnace comprising surrounding walls forming an ashpit, fire-box and combustion chamber, and unbroken continuous U-shaped air conduits in one of the walls of said combustion chamber, and having lateral branches in and along the side walls of the furnace j adjacent the fire-box, said branches being horizontally disposed and having inlets located in the ashpit toward the front thereof and outlets located in the fireboX toward the front thereof, said air conduits being constructed 'toaccommodate said furnace automatically with any system of draft by delivering over the top of the fire therein a quantity of highly'pre-heated air commensurate with the quantity of fuel distributed over the grate therein, together with the rate of the combustion of said fuel and the temperature in said furnace.

9. A -furnace comprising surrounding walls forming an ashpit, lire-box and combustion chamber, and an unbroken continuousv air conduit incased in the walls of said fire-box and combustion chamber, said air conduits being horizontally disposed and having an inlet located below the grate toward the front thereof and having an outlet located above the grate toward the front of said fireboX, said air conduit being constructed to accommodate said furnace automatically with any system of draft'by delivering over the top of the fire therein a quantity of highly pre-heated air commensurate with the quantity of burning fuel therein, together with said air conduits being constructed continuous U-shaped the rate of the combustion of said fuel and the temperature in said furnace.

10. A. furnace comprising surroundingy Walls forming an ashpit, fire-box and combustion chamber, and an unbroken continuous U-shaped air conduit incased in the Walls of said fire-box and combustion chamber, said air conduit being horizontally disposed and having an inlet located in the ashpit toward the front thereof and having an outlet located in the fire-box toward the front thereof, said air conduit being' constructed to accommodate said furnace automatically With any system of draft by delivering Vover the top of the fire therein a quantity oflhighly preheated air commensurate with the quantity of burning fuel therein, together with the rate of the Aamasser combustion of said fuel and the temperature in said furnace.

11. A furnace comprising surrounding Walls forming a fire box, an ash pit and a combustion space, a grate in said furnace, in combination With means to control the flow of the furnace air supply and to direct a portion thereof from below said grate to said re box above the fuel bedv on said grate, said means to direct including an air conduit en cased in one of said walls with an inlet thereto below said grate and an outlet therefrom above said grate.

Signed at Chicago/this 11th day of October, 1920.

IRA W. FOLTZ. 

